Numbers k such that 10^k + 4*R_k + 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102935
Numbers k such that 10^k + 4*R_k + 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =4a(3) =11a(4) =13a(5) =26a(6) =154a(7) =196a(8) =436a(9) =529a(10) =1111a(11) =2563a(12) =2641a(13) =3233a(14) =3883a(15) =4256a(16) =9298a(17) =17293a(18) =23270a(19) =27197a(20) =129826
External references
- oeis: A102935